Dump valve assembly

Abstract

A two-position dump valve for use in a vacuum powered or pressure differential powered cruise control system. The dump valve is closed upon energization of a solenoid, provided the brake pedal is in the brake release position. It opens when the brake pedal is moved to actuate the vehicle brakes.

What is claimed is: 
     
       1. An improved dump valve assembly in combination with a vehicle brake actuator for permitting operation of a differential pressure operated vehicle cruise control system when the brake actuator is in the brake release position and for preventing operation of the vehicle cruise control system when the brake actuator is in the brake actuating position, said valve assembly comprising: a valve defined by a valve seat and a valve element cooperating therewith to close and open said valve to respectively permit operation and prevent operation of the vehicle cruise control system by respectively permitting introduction of a differential pressure into the differential pressure operated vehicle cruise control system and preventing said introduction by dumping the cruise control system to a single pressure;   a first spring continuously exerting a force on said valve element and yieldably acting to hold said valve element in position relative to said valve seat;   a second spring when acting on said valve element exerting a force yieldably tending to urge said valve element away from said valve seat and toward said brake actuator, said second spring exerting a greater force than said first spring so that the position of said valve element relative to said valve seat can be changed by said second spring; and   force-exerting means selectively energizable by initiation of operation of the vehicle cruise control system with said brake actuator in the brake release position to exert a force on said valve element overcoming the force exerted thereon by said first spring and tending to close said valve when said valve is open, the exerted force of said force-exerting means being greater than the force of said first spring but less than the force of said second spring;   said brake actuator operatively and selectively acting on said second spring when in the brake release position to reduce the force of said second spring acting on said valve element at least to an amount which said force-exerting means can overcome when energized to close said valve, and when in the brake applying position permitting said second spring to exert a force on said valve element moving said valve element away from said valve seat in opposition to any forces exerted on said valve element by said first spring and said force-exerting means.   
     
     
       2. The valve assembly of claim 1, said first spring being a drag spring exerting a force on said valve element tending to resist any movement of said valve element from any valve element position to any other valve element position relative to said valve seat.   
     
     
       3. The valve assembly of claim 1, said first spring continuously exerting its force to yieldably urge said valve element in a direction away from said valve seat;   said second spring continuously exerting a force yieldably urging said first spring and, through said first spring, said valve element in a direction tending to further urge said valve element away from said valve seat.   
     
     
       4. A valve assembly comprising: a valve defined by a valve seat and a valve element cooperating therewith to open and close said valve;   first yieldable force-exerting means continuously exerting a first force on said valve element in a direction other than a valve closing direction and yieldably acting to hold said valve element in position relative to said valve seat;   second force-exerting means when acting on said valve element exerting a second force yieldably tending to urge said valve element away from said valve seat, said second force-exerting means exerting a sufficient second force on said valve element so that the position of said valve element relative to said valve seat can be changed by said second force-exerting means;   third force-exerting means selectively energizable to exert a third force acting on said valve element, said third force when so acting overcoming said holding action of said first force exerted on said valve element by said first force-exerting means and acting in a direction tending to close said valve when said valve is open, said exerted third force of said third force-exerting means being greater than said first force of said first force-exerting means but less than said second force of said second force-exerting means whereby said second force can override said third force; and   valve assembly control means including means for selectively energizing and deenergizing said third force-exerting means and other means operatively and selectively acting on said second force-exerting means to reduce the amount of said second force acting on said valve element at least to an amount which said third force can overcome to close said valve when said third force-exerting means is energized.   
     
     
       5. A valve assembly comprising: a valve defined by a valve seat and a valve element movable relative to said valve seat and cooperating therewith to open and close said valve;   a first spring acting on said valve element and exerting a first force on said valve element in other than a valve closing direction and yieldably holding said valve element in a position relative to said valve seat;   a second spring when operatively acting on said valve element exerting a second force urging said valve element away from said valve seat, said second force exerted by said second spring on said valve element being a sufficient force so that the position of said valve element relative to said valve seat can be changed by said second spring;   force-exerting means selectively energizable to exert a third force on said valve element overcoming said first force of said first spring acting on said valve element but less than said second force of said second spring whereby said second force can override said third force; and   valve assembly control means including means for selectively energizing and deenergizing said force-exerting means, and other means operatively and selectively acting on said second spring to reduce the amount of said second force of said second spring acting on said valve element at least to a force level which said third force, generated upon energization of said force-exerting means, can overcome, said third force when said valve is open then causing said valve element to move to engage said valve seat and close said valve irrespective of said first force.   
     
     
       6. A valve assembly comprising: a normally open valve defined by a valve seat and a valve element cooperating therewith to open and close said valve;   first force-exerting means continuously exerting a force yieldably urging said valve element in a direction away from said valve seat;   second force-exerting means continuously exerting a force yieldably urging said first force-exerting means in a direction tending to further urge said valve element away from said valve seat, said second force-exerting means exerting a greater force than said first force-exerting means;   third force-exerting means selectively energizable to exert a force on said valve element overcoming the force exerted thereon by said first force-exerting means and tending to close said valve, the exerted force of said third force-exerting means being greater than the force of said first force-exerting means but less than the force of said second force-exerting means whereby said second force exerting means can override said third force exerting means; and   valve assembly control means including means for selectively energizing and deenergizing said third force-exerting means and other means operatively acting on said second force-exerting means to selectively reduce the force thereof acting on said first force-exerting means to a force level providing only reaction equal to the force exerted by said first force-exerting means, said last named means providing reaction for the remainder of the force exerted by said second force-exerting means.   
     
     
       7. A valve assembly comprising: a normally open valve defined by a valve seat and a valve element movable relative to said valve seat and cooperating therewith to open and close said valve; a first spring acting on said valve element and exerting a force yieldably urging said valve element in a direction away from said valve seat;   a second spring operatively providing reaction for said first spring and exerting a force thereon urging said first spring in a direction tending to further urge said valve element away from said valve seat, said second spring exerting a greater force than said first spring;   force-exerting means selectively energizable to exert a force on said valve element opposing the force of said first spring and greater than the force of said first spring but less than the force of said second spring whereby the force of second spring can override the force of said force-exerting means; and   valve assembly control means including means for selectively energizing and deenergizing said force-exerting means, and other means operatively acting on said second spring to selectively reduce the force thereof acting on said first spring to a force level producing only reaction force equal to the reaction force exerted by said first spring, said other means then providing reaction for the remainder of the force exerted by said second spring.   
     
     
       8. A valve assembly comprising: a housing;   a normally open valve in said housing, said valve being defined by a valve seat on said housing and a valve element movable in said housing relative to said valve seat and cooperating therewith to open and close said valve;   a first spring in said housing operatively acting on said valve element and exerting a force yieldably urging said valve element in a direction away from said valve seat;   a second spring in said housing operatively reacting on said housing and operatively providing reaction for said first spring and operatively exerting a force on said first spring urging said first spring in a direction tending to further urge said valve element away from said valve seat, said second spring exerting a greater total force than said first spring;   a solenoid armature secured to said valve element for movement therewith in said housing;   a solenoid coil in said housing and receiving said solenoid armature and selectively energizable to exert a force on said valve element through said solenoid armature which opposes the force of said first spring and is greater than the force of said first spring but less than the total force of said second spring whereby the total force of said second spring can override the force exerted by said solenoid coil; and   valve assembly control means including means for selectively energizing and deenergizing said solenoid coil and other means operatively selectively acting on said second spring with a reaction force greater than the difference between the total force of the second spring and the force of reaction between said first and second springs to limit the force of said second spring acting on said first spring to a force level providing only reaction force no greater than the reaction force exerted on said second spring by said first spring, said other means then providing reaction for the remainder of the force exerted by said second spring.   
     
     
       9. A valve assembly comprising: a housing having a chamber formed therein, first and second ports opening into said chamber, and a valve seat formed about said first port;   a valve member having a valve element and a valve stem and a valve stem head, said valve member being reciprocably received in said housing for axial movements toward and away from said valve seat so that in a first valve member axial position said valve element cooperates with said valve seat to close said first port and in a second valve member axial position said valve element is axially spaced from said valve seat to open said first port to said chamber and thereby fluidly connect said first and second ports, at least a part of said valve member being a solenoid core;   a solenoid coil mounted in said chamber about said solenoid core and fixed to said housing, said solenoid core when energized magnetically urging said solenoid core and therefore said valve member axially toward said valve seat, thereby tending to close said first port;   a plunger having a bore with a closed end and an open end, said plunger being reciprocably received in said chamber with the closed end thereof extending outwardly of said housing from said chamber in the axially opposite direction from said valve seat, said plunger and said housing having cooperating stops formed thereon limiting movement of said plunger in an axial direction away from said valve seat and outwardly of said housing;   an annular spring seat in said chamber engaging said plunger open end and having said valve stem extending axially therethrough, a portion of said annular spring seat being operatively engageable axially with said valve stem head, said valve stem head being positioned axially within said plunger bore;   a first spring in said chamber operatively acting on said housing and on said spring seat and urging said spring seat and said plunger in a direction axially away from said valve seat;   a second spring in said chamber and also in said plunger bore, said second spring acting on said spring seat and said valve stem head and urging said valve member axially away from said valve seat, said second spring having a spring rate and load incapable of moving said valve member axially in opposition to the magnetic urging of said solenoid when said solenoid is energized;   said first spring having a spring rate and load capable of moving said spring seat and said plunger against the force of said second spring to operatively engage said spring seat and said valve stem head and then to further move said spring seat and said plunger and said valve member axially in opposition to the magnetic urging of said solenoid coil when said solenoid coil is energized; and   control means having a first position engaging said plunger closed end and opposing the force of said first spring to hold said plunger and said spring seat in a position axially toward said valve seat and permitting axial movements of said valve member between and to said valve member first and second axial positions, and a second position disengaged from said plunger;   said second spring holding said valve element away from said valve seat when said control means is in its first position until said solenoid coil is energized to overcome said second spring and axially move said valve element to seat on said valve seat and close said first port, said second spring acting upon deenergization of said solenoid coil to move said valve member to open said valve element relative to said valve port;   said first spring acting upon movement of said control means to its second position to operatively move said valve member to open said first port when said solenoid coil is energized, and to move said spring seat to further load said second spring in the valve opening direction whether or not said solenoid coil is energized.